1. Field of the Invention
The present invention relates to a circuit device board, a semiconductor component, and a method of fabricating the same. More specifically, the circuit device board is fabricated by: forming a first conductor pattern, which determines the function of the circuit device, on one side of a first dielectric substrate having two conductive layers provided on both sides thereof respectively; forming a second conductor pattern, which is substantially identical in the shape to the first conductor pattern when the two patterns are placed one over the other, on one side of a second dielectric substrate having two conductive layers provided on both sides thereof respectively; and bonding the first dielectric substrate and the second dielectric substrate to each other by an adhesive dielectric layer so that the first conductor pattern and the second conductor pattern can overlap each other. Also, while a semiconductor device is connected with the first or second conductor pattern, the first conductor pattern and the second conductor pattern are connected to each other for input and output of signals. Accordingly, a desired level of the frequency response can be obtained regardless of the thickness of the adhesive dielectric layer which joins the two dielectric substrates.
2. Description of the Related Art
For transmission of data at a higher speed over a radio link or a cable line in the sharply developing communications technology, a variety of circuit blocks are installed in relevant apparatuses such as mobile communications instruments, ISDN appliances, or computers.
As equipped with such a circuit block, every arrangement is desired to minimize the effect of noise while conduct the transmission of data at a high speed. It is also essential for portable communications apparatuses to decrease the size of components, have the components integrated, and provide multi-function types of the components. For example, for implementing a functional block in a high-frequency circuit, distributed constant circuits are commonly used for minimizing and integrating filters, high-frequency matching circuits, or coupler circuits, because a VCO (voltage controlled oscillator) or a filter is hardly feasible with the use of semiconductor devices as its wavelength becomes short.
It is known that development at high accuracy of an advanced band-pass filter on a substrate is implemented using a co-planar waveguide or a microstrip which is a planar transmission line with a xc2xcxcex coupling path (xcex being a wavelength). However, such a conventional circuitry arrangement is developed on the surface of a substrate and may thus possibly generate interference with other external circuits. The arrangement may also emit electromagnetic waves causing malfunction of adjacent devices. It is hence necessary for minimizing the effect of electromagnetic waves to shield the entire arrangement or to protect with an electromagnetic waves absorbing material. This will make the arrangement very intricate and increase the overall dimensions, resulting in the cost up. Moreover, the circuitry arrangement is normally developed along a plane and will thus be increased in the size when the frequency is within a relatively lower range.
The circuitry arrangement such as a band-pass filter is modified to have a combination of the step impedance resonance structure and the strip line structure where the signal lines are sandwiched between two grounding conductors for minimizing the effect of electromagnetic waves, whereby its side can be decreased by minimizing the resonator.
FIG. 1 illustrates such a band-pass filter having the step impedance resonance structure, where two dielectric substrates 202 are installed between external grounding conductors 201 while a resonator 203 comprising a couple of signal conductive layers which are different in the impedance is sandwiched between the two dielectric substrates 202. The frequency response of the band-pass filter of FIG. 1 is graphed in FIG. 2 where f0 is a center frequency and WT is a transmissive band width.
A circuit device board incorporating the band-pass filter shown in FIG. 1 is declined in the frequency response if there are generated variations in the thickness of dielectric substrates or in the accuracy of fabricating conductor patterns which determine the function of a circuit device. FIG. 3 illustrates the relation in change between the dielectric substrate thickness and the center frequency. For example, when the dielectric substrate thickness is varied 5%, the center frequency may change substantially 1% to 2%. With 5 GHz of the center frequency of the band-pass filter, the frequency will change up to 100 MHz at maximum and hardly be feasible. For eliminating undesired variations in the frequency response, it is needed to fabricate the substrates and the patterns at a considerable level of accuracy and the band-pass filter will thus be costly.
To decrease the cost of front-end devices of a specific communications apparatus using microwaves or milliwaves, the substrates are formed of organic materials such as fiber glass based epoxy resin or fiber glass based BT bismaleimide-triazine) resin instead of traditional ceramic materials. Such organic substrates are however different and more difficult in the fabrication than the traditional ceramic substrates. Particularly, a layer arrangement of the band-pass filter where a plurality of organic substrates are placed one over another possibly finds difficult in controlling the thickness of an adhesive layer which is a part of the dielectric film and its filtering characteristic will hardly stay at a desired level.
FIGS. 4A and 4B each shows an arrangement including the dielectric substrates made of an organic material. FIG. 4A is an exploded perspective view and FIG. 4B is a schematic cross sectional view taken along the line denoted by PA of FIG. 4A. Referring to FIG. 4A, the arrangement or a band-pass filter employs the two organic substrates 210 and 215. The organic substrate 210 is a double-side printed circuit board of which the joining side (located opposite to the other dielectric substrate 215) has conductor patterns 210a and 210b of a resonance circuit provided thereon. A shield coating 210c is provided on the other side of the organic substrate 210. The other organic substrate 215 is a single-side printed circuit board of which the conductive side is covered with a shield coating 215c. 
As the conductor pattern 210a side of the double-side printed circuit-board 210 comes opposite to the other side of the single-side printed circuit board 215 where the shield coating 215c is not provided, a prepreg 218 for bonding is sandwiched between the double-side printed circuit board 210 and the single-side printed circuit board 215. After pressing and heating the assembly, a step impedance resonance arrangement of the band-pass filter is completed.
The thickness of the double-side printed circuit board 210 or the single-side printed circuit board 215 can easily be controlled at high precision. However, the thickness of the prepreg 218 which is an adhesive dielectric layer for bonding the substrates may significantly be varied depending on the conditions of fabrication and the patterning rate of the printed circuit board and hardly be adjusted to a desired setting.
If the thickness of the prepreg 218 varies, a desired level of the filtering characteristic can rarely be obtained. As the yield of the band-pass filter is declined, the band-pass filter will be high in the cost even when its substrate materials are inexpensive.
It is thus an object of the present invention to provide a circuit device board, a semiconductor component, and a method of the same, of which the characteristic has a desired level with two or more dielectric substrates joined one another.
A circuit device board according to the present invention is provided by: joining a first dielectric substrate having a first conductor pattern provided thereon to a second dielectric substrate having a second conductor pattern provided thereon by an adhesive dielectric layer so that the two conductor patterns come opposite to each other; arranging the first conductor pattern to a circuit device pattern shape for performing a desired function while arranging the second conductor pattern to a shape substantially identical to the first conductor pattern so that the two patterns can overlap each other; and providing a grounding conductor on the outer side of each of the first and second dielectric substrates.
A method of making a circuit device board according to the present invention is provided comprising the steps of: forming a first conductor pattern, which determines the function of the circuit device, on one side of a first dielectric substrate having two conductive layers provided on both sides thereof respectively; forming a second conductor pattern, which is substantially identical in the shape to the first conductor pattern when the two patterns are placed one over the other, on one side of a second dielectric substrate having two conductive layers provided on both sides thereof respectively; and bonding the first dielectric substrate and the second dielectric substrate to each other by an adhesive dielectric layer so that the first conductor pattern and the second conductor pattern can overlap each other.
A semiconductor component according to the present invention is provided by: bonding a first dielectric substrate having a first conductor pattern provided thereon to a second dielectric substrate having a second conductor pattern provided thereon by an adhesive dielectric layer so that the two conductor patterns come opposite to each other; arranging the first conductor pattern to a circuit device pattern shape for performing a desired function while arranging the second conductor pattern to a shape substantially identical to the first conductor pattern so that the two patterns can overlap each other; connecting the first conductor pattern and the second conductor pattern to each other by connecting members; and providing a semiconductor device connected to at least one of the first and second conductor patterns.
A method of making a semiconductor component according to the present invention is provided comprising the steps of: forming a first conductor pattern, which determines the function of a circuit device, on one side of a first dielectric substrate having two conductive layers provided on both sides thereof respectively; forming a second conductor pattern, which is substantially identical in the shape to the first conductor pattern when the two patterns are placed one over the other, on one side of a second dielectric substrate having two conductive layers provided on both sides thereof respectively; and bonding the first dielectric substrate and the second dielectric substrate to each other by an adhesive dielectric layer so that the first conductor pattern and the second conductor pattern can overlap each other, thus connecting the first conductor pattern and the second conductor pattern to each other and the semiconductor device to at least one of the first and second conductor patterns.
Accordingly, when a band-pass filter is developed as the circuit device on one side of a double-side copper laminated board which is the first dielectric substrate having the two conductor layers provided on both sides thereof, the first conductive pattern incorporates a resonator pattern. Also, a resonator pattern which is substantially identical in the shape to the resonator pattern of the first double-side copper laminated board is provided on one side of a second double-side copper laminated board or the second dielectric substrate so that the two patterns is located one over the other. The first and second double-side copper laminated boards are bonded to each other by the adhesive dielectric layer so that their resonator patterns come opposite to each other. Alternatively, a plurality of substantially equally shaped resonator patterns including those of the first and second double-side copper laminated boards may be provided one over another with any two adjacent patterns isolated by an insulating dielectric layer. In addition, the resonator pattern of the first double-side copper laminated board may be joined to the resonator pattern of the second double-side copper laminated board by projected electrodes. The resonator pattern of the first or second double-side copper laminated board may be connected with the semiconductor device such as an MMIC. The semiconductor device may be mounted to outer side of the assembly of the first and second double-side copper laminated boards which are joined to each other by via holes or through holes connected between the resonator patterns. Alternatively, after the resonator pattern of the first or second double-side copper laminated board is connected by bumps with the semiconductor device such as an MMIC, the first double-side copper laminated board and the second double-side copper laminated board are bonded to each other so that the semiconductor device is sandwiched therebetween.